No abstract

Begomoviruses (family Geminiviridae) cause a number of serious diseases of cultivated crops and they are considered as the major constrains for cultivation of several crops all over the world. Presently human activity and modern day agriculture are one of the key factors in the emergence of begomoviruses in various parts of the world. The available disease management options include the organisation of agricultural practice to reduce disease, the use of cultural control such as sanitation programmes, the control of the vector population through the use of insecticides, and the breeding and growing of resistant crop cultivars. Transgenic resistance against begomoviruses has shown limited success despite the use of a number of strategies. Ability of begomoviruses to evolve rapidly by recombination and mutations is the major limitation to all these strategies. In modern-day biotechnology, focus is required on engineering begomovirus resistance through transgenic approach. Expression of various full length or truncated or defective proteins of the virus has been effective in achieving pathogen-derived resistance. Antisense RNA and RNAi technology have also been used with some success. This review focus on both conventional and nonconventional management strategies methods have been suggested and described over the years for management of begomoviruses diseases in economically important plants.

Incidence of yellow vein net disease with leaf distortion was observed on Malva parviflora grown as a weed in Barkatullah University campus, Bhopal, India during the rainy session. The begomovirus disease was suspected on the basis of symptomatology and whiteflies insects' population on the plant. The begomovirus was detected by the PCR with the begomovirus gene specific primers. The begomovirus under study showed highest nucleotide sequence identities and distinct phylogenetic relationships of coat protein gene (CP) with several isolates of Tomato leaf curl Kerala virus (ToLCKeV). This is the first report of ToLCKeV associated with yellow vein net disease on M. parviflora and it is a new host of begomovirus from India.

Severe witches'-broom disease of Ziziphus oenoplia was observed with significant disease incidence in Bhopal, India, during 2019. Phytoplasma was detected from symptomatic leaf samples by polymerase chain reaction (PCR) using phytoplasma 16S rRNA gene specific primers which revealed positive amplification of expected size ~1.2 kb DNA band. The positive amplicons of the phytoplasma 16S rRNA (1.2 kb) were sequence and sequenced data was submitted in GenBank database (Accession no. MK975463 and MK975462). On the basis of highest 99% sequence identities, closest phylogenetic relationships and In silico of the under study both the phytoplasma isolates associated with witches'-broom disease of Ziziphus oenoplia identified as a species of Jujube witches'-broom phytoplasma as a member of Elm yellows group (16SrV ). To the best of our knowledge, this is the first report on the association of Jujube witches'-broom phytoplasma species of Elm yellows group (16SrV) with witches'-broom disease of Z. oenoplia in India.